1. Field of the Invention
The present invention relates to a liquid crystal cell filled with smectic liquid crystal such as ferroelectric or antiferroelectric liquid crystal for displaying images thereon, and to a method of manufacturing the liquid crystal cell.
2. Related Arts
Conventionally, to fill a liquid crystal cell with smectic liquid crystal, the liquid crystal cell is disposed in a vacuum chamber and smectic liquid crystal is put on a vicinity of a liquid crystal suction port of the liquid crystal cell. Then, the vacuum chamber is evacuated while heated, so that the inside of the liquid crystal cell becomes a vacuum state. Accordingly, smectic liquid crystal changes to be an isotropic phase and expands around the liquid crystal suction port. Thereafter, the pressure in the vacuum chamber is released to an atmospheric pressure so that a difference in pressure between outside and inside of the liquid crystal cell is produced. Due to the difference in pressure, smectic liquid crystal is sucked into the liquid crystal cell through the liquid crystal suction port. Then, the temperature of the liquid crystal cell filled with smectic liquid crystal is returned to a room temperature.
At the room temperature, however, the phase of smectic liquid crystal changes from the isotropic phase to a smectic phase (for example, smectic A phase). This transition is accompanied by volumetric shrinkage of smectic liquid crystal (see FIG. 5). Consequently, vacancies in which smectic liquid crystal does not exist are produced within the liquid crystal cell, resulting in deterioration of display performance such as display irregularity.
To solve the problem, JP-A-6-51258 proposes a method of compulsorily supplying smectic liquid crystal into a liquid crystal cell filled with smectic liquid crystal under pressure. In this method, however, the liquid crystal cell is heated so that smectic liquid crystal therein has the isotropic phase to produce a constant pressure therein. In this state, smectic liquid crystal is supplied into the liquid crystal cell. Thereafter, the temperature of the liquid crystal cell is lowered to the room temperature, and the pressure applied to the liquid crystal cell is decreased to the atmospheric pressure.
By lowering the temperature to the room temperature the phase of smectic liquid crystal changes from the isotropic phase to the smectic phase again, resulting in volumetric shrinkage. At that time, smectic liquid crystal is not supplied into the liquid crystal cell, because the pressure around the liquid crystal cell is decreased to the atmospheric pressure. Consequently, the liquid crystal cell cannot be completely prevented from having vacancies therein.